Cellular Classification
Primary intraocular melanomas originate from melanocytes in the uveal tract.[1] Four distinct cellular types are recognized in intraocular melanoma (revised Callendar classification):[2]
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Spindle A cells (spindle-shaped cells with slender nuclei and lacking visible nucleoli).
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Spindle B cells (spindle-shaped cells with larger nuclei and distinct nucleoli).
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Epithelioid cells (larger polygonal cells with one or more prominent nucleoli).
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Intermediate cells (similar to but smaller than epithelioid cells).
Most primary intraocular melanomas contain variable numbers of epithelioid, spindle A, and spindle B cells (mixed-cell melanomas). Pure epithelioid-cell primary melanomas are infrequent (approximately 3% of cases).[1] In the Collaborative Ocular Melanoma Study, mixed-cell type melanomas predominated (86% of cases).[3]
Several microscopic features can affect the prognosis of intraocular melanoma, including cell type, mitotic activity, lymphocytic infiltration, and, possibly, fibrovascular loops.[1] Cell type remains the most often used predictor of outcome following enucleation, with spindle A cell melanomas carrying the best prognosis and epithelioid cell melanomas carrying the worst.[1,4]
References
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Klintworth GK, Scroggs MW: The eye and ocular adnexa. In: Sternberg SS, ed.: Diagnostic Surgical Pathology. Philadelphia, Pa: Lippincott Williams & Wilkins, 1999, pp 994-6.
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Grossniklaus HE, Green WR: Uveal tumors. In: Garner A, Klintworth GK, eds.: Pathobiology of Occular Disease: A Dynamic Approach. 2nd ed. New York, NY: M. Dekker, 1994, pp 1423-77.
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Histopathologic characteristics of uveal melanomas in eyes enucleated from the Collaborative Ocular Melanoma Study. COMS report no. 6. Am J Ophthalmol 125 (6): 745-66, 1998.
[PUBMED Abstract]
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McLean IW: Prognostic features of uveal melanoma. Ophthalmol Clin North Am 8 (1): 143-53, 1995.
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